title: In vitro screening of selected feed additives, plant essential oils and plant extracts for rumen methane mitigation.
abstract: BACKGROUND
  Ruminants produce large quantities of methane in their rumen as a by-product of microbial digestion of feed. Antibiotics are added to ruminant feed to reduce wasteful production of methane; however, this practice has some downsides. A search for safer and natural feed additives with anti-methanogenic properties is under way. The objective of this research was to examine selected feed additives, plant essential oils and plant extracts for their anti-methanogenic potential in the rumen using an in vitro batch fermentation system.
  
  
  RESULTS
  A significant reduction (P < 0.05) in methane production was observed with nine feed additives (up to 40% reduction), all eight essential oils (up to 75% reduction) and two plant extracts (14% reduction) when compared to their respective controls. Amongst these, only an algal meal high in docosahexaenoic acid, preparations of Nannochloropsis oculata, calcareous marine algae, yeast metabolites and two tannins did not inhibit microbial gas and volatile acid production.
  
  
  CONCLUSIONS
  The current study identified some potent dietary ingredients or plant compounds that can assist in developing novel feed additives for methane mitigation from the rumen.
authors.affiliation: School of Animal Biology, The University of Western Australia M085, 35 Stirling Hwy, Crawley, WA, 6009, Australia; Future Farm Industries CRC, The University of Western Australia M081, 35 Stirling Hwy, Crawley, WA, 6009, Australia.
authors.forename: Zoey
authors.initials: Z
authors.lastname: Durmic
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Moate
authors.forename: Richard
authors.initials: R
authors.lastname: Eckard
authors.forename: Dean K
authors.initials: DK
authors.lastname: Revell
authors.forename: Richard
authors.initials: R
authors.lastname: Williams
authors.forename: Philip E
authors.initials: PE
authors.lastname: Vercoe
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet; D004063:Digestion; D002523:Edible Grain / Q000378:metabolism; D005285:Fermentation / Q000187:drug effects; D005503:Food Additives / Q000494:pharmacology*; D008697:Methane / Q000096:biosynthesis*; D009822:Oils, Volatile / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D012417:Rumen / Q000187:drug effects* / Q000378:metabolism; D012418:Ruminants / Q000378:metabolism; D058009:Stramenopiles; D013634:Tannins; D015003:Yeasts
chemical_list: D005503:Food Additives; D009822:Oils, Volatile; D010936:Plant Extracts; D013634:Tannins; D008697:Methane
keywords: essential oils; feed additives; plant extracts; rumen methane